HelloToday I update my mac to the last version of Mac OS Mountain Lion.The problem is now after open the IDE on Ports Menu it wont show the arduino Serial Port /dev/tty.USB0 as expectedSoo now I cant upload codes.I also try to connect my ftdi232RL mini board and it is not displayed to in the IDEAnyone else already upgrade to this version?If I go to mac system info it shows this:

Warning: the old crashing problem is introduced once again. So if you are sending Serial data don't disconnect the USB before closing the terminal or your mac will crash!!! For me this is the only way I can crash my mac in normal use b.t.w., I have never experienced it in other situations!

Know this is an old thread but the title is popular with people with a similar issue and there are lots of them it seems.

What worked for me is to look in the /Library/Extensions/Java/Extensions I found a file RXTXcomm.jar in there (from 2006) I trashed it and re-started Arduino... success! took me many hours to find it. You may have to show hidden files in the finder which requires Terminal and the following command (defaults write com.apple.finder AppleShowAllFiles TRUE) when done replace TRUE with FALSE and you're back to normal.

Since your original post come up to the top of Google search I hope this works for others too.

What worked for me when the USBmodem port stopped showing was pretty simple, but easy to overlook since the steps are specific. It requires getting the Arduino to reset by removing all power and allowing the Arduino port to reset when the IDE restarts:

1) unplug from the Arduino the power cable (if being used) and USB cable; all power needs to be removed from the Arduino 2) quit the IDE if it's running 3) re-attach the USB cable to the Arduino (***but don't attach the Arduino power cable yet***)4) restart the IDE

Check the USBmodem port is now showing up as a menu option. If it is, now you can re-attach the power cable to the Arduino.

Hope this works for others... I thought this would work because my Mega had the problem. When I plugged in my Uno (after restarting the IDE) the USBmodem port appeared, however, when plugging the Mega in, the port disappeared. That's when I realized the problem was with the Mega and not my Mac drivers.

1) unplug from the Arduino the power cable (if being used) and USB cable; all power needs to be removed from the Arduino 2) quit the IDE if it's running 3) re-attach the USB cable to the Arduino (***but don't attach the Arduino power cable yet***)4) restart the IDE

Too bad, this doesn't work for me :-(And sorry for diggin' in old threads!